That is pretty interesting.
However, the link says that he committed the murders on 10/28/74; I think that TCM was released before that. So it's unlikely that the filmmakers were influenced by him.
I just did a Lexis/Nexis search on him but am unable to come up with any criminal documents. However I did find his rejected appeal, which I saved on my web site
here. It gives some details of the case, including the location, which is pretty close to the new Austin, Texas airport.